Information downloading apparatus and mobile terminal

ABSTRACT

A technique for improving the efficiency of downloading transmission data is disclosed. An information downloading apparatus downloads differing sets of information to predetermined groups to which a mobile terminal may belong. This apparatus includes a channel selecting unit for selecting from plural information channels an information channel for transmitting transmission data and a transmitting unit for transmitting transmission data using the selected information channel. The channel selecting unit selects an information channel so that sets of transmission data with differing destination addresses may be transmitted through differing information channels. The transmitting unit transmits to each group, through a control channel, information pertaining to whether a set of transmission data exists, the information channel to be used if the set of transmission data exists, and the data length of the set of transmission data. The control channel includes time slots that are associated with the groups.

CROSS REFERENCE TO RELATED APPLICATIONS

This application corresponds to a U.S. continuation application filedunder 35 USC 111(a) claiming benefit under 35 USC 120 and 365 (c) of PCTapplication JP2002/009725, filed on Sep. 20, 2002 and is related to andclaims benefit of U.S. Ser. No. 11/020,629, filed Dec. 27, 2004, nowpending, both of which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a technique for downloadingidentical information to plural mobile terminals, and particularly to aninformation downloading apparatus and a mobile terminal.

2. Description of the Related Art

In the above-described technical field, broadcasting technology forrealizing simultaneous transmissive communication with respect to allmobile terminals, or multicast technology for realizing simultaneoustransmissive communication with respect to mobile terminals that belongto a predetermined group may be used, for example.

FIG. 1 is a conceptual diagram illustrating an example of informationdownloading using multicast technology. In FIG. 1, a control channel 10that is made up of time slots that are respectively assigned to variousmulticast groups, and a message channel 12 for actually downloadinginformation in relation to the control channel 10 are shown. The controlchannel 10 is arranged into a repetition of super frames 14, and N timeslots that are numbered from 0 to N−1, respectively, are included ineach super frame 14. N (>0) may be set according to the number ofdifferent types of downloading information that are provided, anddesignates the number of groups to which a mobile terminal may belong.

FIG. 2 is a table illustrating the relation between a time slot numberand a group (information content). For example, if informationdownloading pertaining to weather forecast is desired, a mobile terminalmay be required to subscribe to the multicast group corresponding toslot number 1.

Referring back to FIG. 1, a mobile terminal may receive control channelinformation pertaining to the group to which it belongs. Suchinformation may only be transmitted through a predetermined timeslot.Thereby, the mobile terminal may conserve its battery energy throughintermittent reception to receive control data from the control channelonly during the period corresponding to the time slot of the pertinentgroup to which the mobile terminal belongs. For example, if the mobileterminal belongs to the weather forecast group, it may receive signalsfrom the control channel during the period of time slot 1, and may beconfigured to refrain from receiving signals during the periods of theother time slots. The control channel 10 includes information indicatingwhether download information exists, and the mobile terminal may beconfigured to extract this information. If it is determined that thereis no transmission information, the mobile terminal may go back to astandby mode to receive the next control data from the control channel.On the other hand, if it is determined that transmission informationexists, the mobile terminal may receive the transmission informationthat is transmitted through the message channel 12 after a predeterminedtime (offset time) elapses from the time slot 1 (i.e., after time t1).Similarly, mobile terminals belonging to other groups may also receivedesired information using the control channel that indicates theexistence of transmission information and the message channel 12 (e.g.,if the desired information corresponds to baseball information, theinformation is transmitted after time t2; and if the desired informationcorresponds to stock information, the information is transmitted aftertime t3).

Japanese Laid-Open Patent Publication No. 2000-224648 relating toinformation downloading discloses a technique for creating a broadcastchannel that is dedicated to broadcasting using a predetermined timeslot from time slots provided for a control channel and a communication(message) channel, and transmitting broadcast data via this broadcastchannel to thereby simultaneously transmit the broadcast data to pluralmobile terminals.

However, in such prior art example, the time slots used for theinformation downloading implements a fixed signal format that is setbeforehand. Thereby, the amount of information to be downloaded and thetransmission time are likely to be restricted by the pre-set time slots.To transmit additional information that cannot be accommodated within apredetermined time slot, the information may be divided into differenttime slots of super frames and transmitted using each time slot assignedto the current group that appears in each super frame 14. Theinformation may then be recombined at the reception side. However, insuch case, additional processes are required for dividing andrecombining the information. This is inconvenient for a mobile terminal,which is preferably configured to conserve energy consumption. Also,another problem is the fact that much time is required for all theinformation to be accumulated at the reception side.

Alternatively, instead of dividing and transmitting information inaccordance with the format of the super frames, for example, weatherforecast information that is originally intended to be transmitted usingone time slot may be transmitted using two time slots (i.e., during theperiod from time t1 to time t3) so that the weather forecast informationmay be transmitted at once instead of having to be divided. However, insuch case, the baseball information may not be transmitted attransmission time t2 as is originally intended (since the weatherforecast information is being transmitted), and thereby, thisinformation may not be transmitted until the next transmission time t2of time slot 2 in the next super frame 14. Accordingly, when attemptingto transmit more than the predetermined amount of information, theinformation downloading time for the current group or another group maybe increased, and thereby, the efficient downloading may not always berealized.

It is also noted that information to be transmitted does not alwaysrequire one time slot's worth of communication resources. However, evenin the case of downloading information that does not reach the capacityof one time slot, since a pre-set fixed signal format is used,information resources are allotted in time slot units. Thus, efficientdownloading may not always be obtained in regard to communicationresource usage efficiency, for example.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to improvedownloading efficiency of transmission data.

The present invention, according to one aspect, provides an informationdownloading apparatus that downloads differing sets of information topredetermined groups to which a mobile terminal may belong, theapparatus including:

a buffer configured to receive sets of transmission data addressed tothe groups;

a scheduler configured to select from a plurality of informationchannels an information channel for transmitting a set of transmissiondata of the sets of transmission data received at the buffer, theselection being made so that the sets of transmission data withdiffering destination addresses are transmitted using differinginformation channels; and

a transmission unit for transmitting the set of transmission data usingthe selected information channel, the transmission unit being configuredto transmit to each of the groups, through a control channel,information pertaining to whether a set of transmission data exists, theinformation channel to be used if the set of transmission data exists,and a data length of the set of transmission data, the control channelincluding a plurality of time slots that are associated with the groups.

The present invention, according to another aspect, provides aninformation downloading apparatus that downloads differing sets ofinformation to predetermined groups to which a mobile terminal belongs,the apparatus including:

a buffer configured to receive sets of transmission data addressed tothe groups;

a scheduler configured to determine a transmission timing fortransmitting the sets of transmission data to the groups according todata length information of the sets of transmission data stored in thebuffer; and

a transmission unit for transmitting the sets of transmission datathrough an information channel according to conditions set by thescheduler, the transmission unit being configured to transmit to each ofthe groups, through a control channel, information pertaining to whethera set of transmission data exists, a transmission timing for the set oftransmission data if the set of transmission data exists, and a datalength of the set of transmission data, the control channel including aplurality of time slots that are associated with the groups.

The present invention, according to another aspect, provides, aninformation downloading apparatus, including:

a control channel having a plurality of time slots; and

an information channel for downloading download information that isassigned to the time slots of the control channel;

wherein the time slots of the control channel include identificationinformation for specifying the information channel that is to be used todownload a set of download information.

In one embodiment of the present invention, the set of downloadinformation to be downloaded by the information channel may betransmitted after a predetermined offset time period elapses withrespect to a corresponding time slot of the control channel.

According to another embodiment of the present invention, theidentification information of the control channel may includeinformation pertaining to a channel number and a data length.

The present invention, according to another aspect, provides aninformation downloading apparatus including:

a control channel having a plurality of time slots; and

an information channel for downloading download information that isassigned to the time slots of the control channel;

wherein the time slots of the control channel include identificationinformation for specifying a download timing for downloading a set ofdownload information.

According to one embodiment of the present invention, the identificationinformation may include information pertaining to an offset time periodwith respect to a corresponding time slot of the control channel, theoffset information being used to prevent overlapping of differing setsof download information.

The present invention, according to another aspect, provides aninformation downloading apparatus that downloads differing sets ofinformation to predetermined groups to which a mobile terminal belongs,the apparatus including:

a channel selecting unit (scheduler) configured to select from aplurality of information channels an information channel fortransmitting a set of transmission data, the selection being made sothat sets of transmission data with differing destination addresses aretransmitted through differing information channels; and

a transmission unit for transmitting the set of transmission data usingthe selected information channel, the transmission unit being configuredto transmit to each of the groups, through a control channel,information pertaining to whether a set of transmission data exists, aninformation channel to be used if the set of transmission data exists,and a data length of the set of transmission data, the control channelincluding a plurality of time slots that are associated with the groups.

The present invention, according to another aspect, provides aninformation downloading apparatus that downloads differing sets ofinformation to predetermined groups to which a mobile terminal belongs,the apparatus including:

a transmission timing determination unit (scheduler) configured todetermine a transmission timing for transmitting sets of transmissiondata addressed to the groups according to data length information of thesets of transmission data;

a transmission unit for transmitting the sets of transmission datathrough an information channel according to conditions set by thetransmission timing determination unit, the transmission unit beingconfigured to transmit to each of the groups, through a control channel,information pertaining to whether a set of transmission data exists, atransmission timing of the set of transmission data if the transmissiondata exists, and a data length of the set of transmission data, thecontrol channel including a plurality of time slots that are associatedwith the groups.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a prior art example of informationdownloading using multicast technology;

FIG. 2 is a table illustrating an exemplary correspondence between atime slot number and a multicast group;

FIG. 3 is a block diagram showing a configuration of an informationdownloading apparatus according to a first embodiment of the presentinvention;

FIG. 4 is a diagram illustrating a control channel that is used in thefirst embodiment of the present invention;

FIG. 5 is a diagram showing an exemplary set of a control channel andinformation channels that may be used in the first embodiment;

FIG. 6 is a block diagram showing a configuration of a portion of amobile terminal that may be suitably used in the first embodiment;

FIG. 7 is a block diagram showing a configuration of an informationdownloading apparatus according to a second embodiment of the presentinvention;

FIG. 8 is a diagram showing an exemplary set of a control channel and aninformation channel that may be used in the second embodiment;

FIG. 9 is a block diagram showing a configuration of a portion of amobile terminal that may be suitably used in the second embodiment;

FIG. 10 is a block diagram showing a configuration of an informationdownloading apparatus according to a third embodiment of the presentinvention;

FIG. 11 is a block diagram showing a configuration of a portion of amobile terminal that may be suitably used in the third embodiment;

FIG. 12 is a block diagram showing a configuration of an informationdownloading apparatus according to a fourth embodiment of the presentinvention;

FIG. 13 is a diagram showing an exemplary set of a main control channel,a sub control channel, and information channels that may be used in thefourth embodiment;

FIG. 14 is a block diagram showing a configuration of a portion of amobile terminal that may be suitably used in the fourth embodiment;

FIG. 15 is a block diagram showing a configuration of an informationdownloading apparatus according to a fifth embodiment of the presentinvention;

FIG. 16 is a diagram showing an exemplary set of a control channel andan information channel that may be used in the fifth embodiment;

FIG. 17 is a block diagram illustrating a configuration of a portion ofa mobile terminal that may be suitably used in the fifth embodiment; and

FIG. 18 is a diagram showing an exemplary set of control channels andinformation channels that may be used in a sixth embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, preferred embodiments of the present invention aredescribed with reference to the accompanying drawings. It is noted that,for the sake of convenience, the preferred embodiments of informationdownloading apparatuses illustrated below are described as beingimplemented in a base station apparatus that establishes wirelesscommunication with a mobile terminal. However, the informationdownloading apparatus of the present invention is not limited to such anarrangement and may be implemented in a base station control apparatusthat controls the base station, or some other superordinate apparatus ofthe base station, for example. Alternatively, at least a portion of thefunctions of the information downloading apparatus of the presentinvention may be implemented in the base station and/or a superordinateapparatus of the base station.

First Embodiment

FIG. 3 is a block diagram showing an information downloading apparatus300 according to a first embodiment of the present invention. In thisexample, information transmitted from a network (not shown) through asuitable interface (not shown) is stored in a buffer 302. The buffer 302is coupled to a scheduler 304. The scheduler 304 is coupled to a controlchannel generating unit 308 that forms a part of a transmission unit306. At the control channel generating unit 308, a control channel isgenerated using time slots that are associated with different multicastgroups. In this way, control data may be transmitted to each group.Also, a control channel timing generating unit 310 provides informationpertaining to the time slots and the transmission timing to thescheduler 304 and the control channel generating unit 308.

The buffer 302 may be coupled to an information channel 1 generatingunit 314, an information channel 2 generating unit 316, or aninformation channel 3 generating unit 318 via a selector 312. Theinformation channels correspond to communication resources that may beallotted using frequencies and spread codes, for example. In the presentembodiment, predetermined channel numbers are used to identify theinformation channels; however, it is noted that the present invention isnot limited to the use of channel numbers and any identificationinformation that is capable of identifying an information channel may beused. The selector 312 uses a channel number from the scheduler 304 aswell as timing information from the information channel timinggenerating unit 320 to conduct a selection operation. As is illustrated,the control channel generating unit 308, the selector 312, theinformation channel generating units 314, 316, and 318 for theinformation channels 1, 2, and 3, respectively, are comprehensivelyincluded in the transmission unit 306. That is, the output of thetransmission unit 306 includes the output from the control channelgenerating unit 308, and the respective outputs from the informationchannel generating units 314, 316, and 318 for the information channels1, 2, and 3. These outputs are output from an antenna (not shown) as acontrol channel and information channels, respectively.

In the following, the operation of the information downloading apparatus300 is described. The buffer 302 receives transmission data that aretransmitted as download information, and provides information pertainingto the amount of transmission data (buffer amount) for each multicastgroup to the scheduler 304. In turn, the scheduler 304 first determineswhether download information exists for each group (informationexistence), and reports the determination result to the control channelgenerating unit 308. If it is determined that there is no downloadinformation for a given group, control data indicating the fact that nodownload data exist are generated at the control channel generating unit308.

On the other hand, if it is determined that download information existsfor a given group, the scheduler 304 selects from plural informationchannels one information channel that is suitable for downloading thecorresponding information based on the data length of the transmissiondata. That is, after a predetermined period of time elapses from the endof the time slot (information channel) for the given group, aninformation channel that is capable of transmitting the downloadinformation is selected. In a case where there are plural informationchannels as candidates for conducting the transmission, the informationchannel with a smaller channel number may be selected in the presentexample. However, it is noted that this arrangement is not aprerequisite of the present invention and any of the any informationchannel suitable for the corresponding download information transmissionmay be used. Also, it is noted that in the present example, thepredetermined period of time corresponds to a fixed offset time periodthat is set in the system beforehand. After the selection of theappropriate information channel, information pertaining to the selectedinformation channel is conveyed to the control channel generating unit308. In this way, information pertaining to the existence oftransmission data, and in the case where the transmission data exist,the information channel to be used and the data length of thetransmission data are transmitted to each group via a control channel.

The data length may correspond to an arbitrary value. The data lengthmay be specified by the number of time slots as well as the number ofbits, bytes, chips, and other forms of time units. In this way, largeamounts of data may be consecutively downloaded. Also, precise resourceallocation may be conducted with respect to small amounts of data thatmay not completely take up one slot.

FIG. 4 shows the contents of the control channel included in the outputfrom the control channel generating unit 308. In the present example,each time slot 602 corresponds to each one of the plural multicastgroups. In this way, information pertaining to the existence oftransmission data (information existence) 604, the information channelto be used if the transmission data exist (channel number) 606, and thedata length 608 of the transmission data are transmitted for each group.The control channel may also include CRC (Cyclic Redundancy Check) bits610 for conducting error detection; however, the CRC is not aprerequisite of the present invention. It is noted that FIG. 4 is not arepresentation of a precise signal format of the control channel, and israther a representation of the contents that may be included in thecontrol channel. Accordingly, the order of the items within the controlchannel may be suitably adjusted, and also, other information items maybe added as necessary or desired.

Referring back to FIG. 3, information pertaining to the selectedinformation channel (channel number) is conveyed to the control channelgenerating unit 308, as well as the selector 312, and this informationchannel is used for transmission of the download information. In thisway, download information from the buffer 302 is transmitted through theselector 312 to be output from the information channel generating units314, 316, and 318 for the information channels 1, 2, and 3, based on thetiming from the information channel timing generating unit 320. In thepresent embodiment, the information download apparatus 300 isimplemented in a wireless base station, and thereby, the outputinformation channels may be transmitted through wireless transmissionalong with the control channel. If the information downloading apparatus300 is implemented as a superordinate apparatus of the base station, theoutputs from the transmission unit 306 may be transmitted to the basestation as control data and information data so that the data may inturn be transmitted from the base station as a control channel andinformation channels.

FIG. 5 is a diagram illustrating an exemplary set of a control channeland information channels that are output and transmitted from thetransmission unit 306. As is shown, the control channel is made up of Ntime slots that may have values such as 256 or 1024, for example, andeach time slot is associated with one of the multicast groups. Thecontents transmitted by the control channel may correspond to the outputfrom the control channel generating unit 308 of FIG. 3. The N number oftime slots may make up a super frame 402 as a whole, and control datapertaining to information downloading may be continually transmitted asa repetition of the super frames 402.

In the following description, it is assumed that the correspondencebetween a time slot and a multicast group as indicated in FIG. 2 isapplied. According to the example of FIG. 5, in time slot 0 it isindicated that, download information pertaining to the news exists, andaccordingly, after a predetermined offset time period Td elapses fromthe end of time slot 0, this download information is transmitted throughinformation channel 1. This information corresponds to the output of theinformation channel 1 generating unit 314 of FIG. 3. Also, in time slot1, it is indicated that download information pertaining to weatherforecast exists, and accordingly, after a predetermined time period Tdelapses from the end of time slot 1, this download information istransmitted through information channel 2. This information correspondsto the output of information channel 2 generating unit 316 of FIG. 3. Intime slot 2, it is indicated that information pertaining to baseballdoes not exist, and thereby, no information is transmitted from theinformation channel. In time slot 3, it is indicated that downloadinformation pertaining to stocks exists, and accordingly, after apredetermined offset time period Td elapses from the end of time slot 3,this download information is transmitted through information channel 3.This information corresponds to the output of the information channel 3generating unit 318.

In the above example, if the scheduler 304 is configured to select aninformation channel with a smaller channel number in a case where pluralusable information channels exist, the information channel 1 may be usedinstead of the information channel 3 to transmit the stock information.Also, it is noted that although the predetermined offset time period Tdis illustrated as being equivalent to the time period of one time slotin the present embodiment, such an arrangement is not a prerequisite ofthe present invention, and any suitable time period may be set as theoffset time period.

FIG. 6 is a block diagram illustrating a configuration of a portion of amobile terminal 500 that may be suitably used in the first embodiment ofthe present invention. The mobile terminal 500 includes a controlchannel decoding unit 502 for decoding control data included in a signalreceived via an antenna (not shown). The output of the control channeldecoding unit 502 is coupled to a determination unit 504 that determineswhether download information exists. The output of the determinationunit 504 is coupled to an information channel timing generating unit 506corresponding to management means for controlling the reception timingof information channels. The control channel decoding unit 502 and theinformation channel timing generating unit 506 are coupled to a controlchannel timing generating unit 507 for controlling the timing pertainingto the control channel. Also, the output of the control channel decodingunit 502 is coupled to a unit 508 for extracting the data length of thedownload information, and a unit 510 for extracting a channel number ofthe information channel to be used for transmitting the downloadinformation.

The units 508 and 510 are includes in an extraction unit 512, which isconfigured to extract control data other than data pertaining to theexistence of download information. The output from the unit 510concerned with the channel number is coupled to a switching unit 514 forswitching to a channel designated by the unit 510 from among pluralinformation channels. The output of the channel switching unit 514 isinput to an information channel decoding unit 516 that is configured tooutput information data. The channel switching unit 514 and theinformation channel decoding unit 516 form a reception unit 518 forreceiving the download information at the appropriate reception timingusing the information channel designated by the control channel.

In the following, the operation of the mobile terminal 500 is described.The mobile terminal 500 receives control data for the multicast group towhich it belongs through intermittent reception. Upon subscribing to amulticast group, the mobile terminal 500 acquires information pertainingto the time slot and the corresponding information thereof that it is toacquire. Using this information, the control channel timing generatingunit 507 generates the reception timing for conducting the intermittentreception. A reception signal that is received from an antenna isdemodulated by a demodulating circuit (not shown), and control data froma control channel are input to the control channel decoding unit 502,and decoded thereat. Then, the determination unit 504 determines whetherdownload information exists. If it is determined that downloadinformation does not exist, this determination result is reported to theinformation channel generating unit 506, and the mobile terminal 500waits for the arrival of the next set of control data. On the otherhand, if it is determined that download information exists, theextraction unit 512 extracts additional information from the controldata pertaining to the data length of the download information, and theinformation channel to be used for the information downloading (channelnumber). The information pertaining to the existence of the downloadinformation and the data length thereof are conveyed to the informationchannel generating unit 506. The information pertaining to theinformation channel to be used for the information downloading isconveyed from the extracting unit 512 to the channel switching unit 514so that the channel may be set to the appropriate information channel.Then, the decoding unit 516 receives the download information based onthe reception timing from the information channel generating unit 506,and decodes the received information to obtain information data.

For example, assuming that the mobile terminal 500 belongs to the groupfor news information, the mobile terminal 500 receives control data fortime slot 0, decodes the data at the control channel decoding unit 502,and determines that download information exists at the determinationunit 504. Thus, the extracting unit 512 extracts further information onthe transmission data to determine that the data length of thetransmission data is 20 ms, and the information channel 1 is to be usedto conduct the information downloading. Then, the mobile terminal 500receives the news information that is transmitted after thepredetermined offset time period elapses from the end of the time slot 0using the information channel 1.

According to the present embodiment, plural information channels areused to transmit download information. The information channel to beused for transmitting download information for a given group is conveyedto each group through a control channel. The manner in which the pluralinformation channels are to be used may be suitably determined by thescheduler 304 within the information downloading apparatus 300 so thatdownloading efficiency may be improved.

It is noted that the embodiment described above is illustrated as havingthree information channels. However, the present invention is notlimited to this arrangement, and any number of information channels thatare defined by a frequency, a code, or a combination thereof, forexample, may be used. Also, it is noted that although a common channelthat may be shared by all users is conventionally used as theinformation channel, in some cases, a unique channel that is exclusivelyused by a single user may be used as well. That is, the informationchannel is concerned with appropriately transmitting downloadinformation, and thereby, the present invention may use a common channelor a unique channel, or use a unique channel when such channel isalready established and use a common channel when a unique channel isnot established. On the other hand, the control channel is concernedwith controlling the intermittent operations of mobile terminalsbelonging to various groups, and thereby, a common channel shared bythese mobile terminals and including time division time slots has to beused as the control channel.

Second Embodiment

FIG. 7 is a block diagram illustrating a configuration of an informationdownloading apparatus 700 according to a second embodiment of thepresent invention. It is noted that elements of the present embodimentthat are identical to those of the first embodiment are assigned thesame numerical references and descriptions thereof are omitted. Theinformation downloading apparatus 700 includes a buffer 302 and ascheduler 704 that is coupled to the buffer 302. The scheduler 704determines, based on information pertaining to the amount of data fromthe buffer 302, whether download information exists and the data lengththereof if such download information exists as in the first embodiment.The scheduler 704 differs from the first embodiment in that it conveysto a control channel generating unit 708 information pertaining to atime period that is to elapse from the end of a time slot after whichdownload information may be transmitted (offset), such information beingprimarily based on the data length of the download information. In otherwords, according to the present embodiment, the offset is not set to afixed value, and is rather a variable that may dynamically vary for eachgroup. The offset information is also conveyed to an information channeltiming generating unit 720, which in turn generates the transmissiontiming for the download information. Using this transmission timing, aninformation channel generating unit 314 transmits transmission data thatare stored in the buffer 302.

FIG. 8 illustrates an exemplary set of a control channel and aninformation channel that may be output from the transmission unit 306according to the present embodiment. In this example, the controlchannel includes N time slots numbered from 0 to N−1, and is configuredto transmit sets of control data for the respective groups associatedwith the time slots. In the present embodiment, information pertainingto the existence of download data, the offset, and the data length aretransmitted as the control data to each group. For example, in time slot0, it may be indicated that download information pertaining to the newsexists, and accordingly, this download information may be transmittedafter the elapse of a certain time interval (T₀) from the end of thetime slot 0. In time slot 1, it may be indicated that informationpertaining to weather forecast does not exist. In time slot 2, it may beindicated that information pertaining to baseball exits, andaccordingly, the download information may be transmitted after theelapse of a certain time interval (T₂) from the end of the time slot 2.It is noted that the values of the time intervals T₀ and T₂ arevariable, and may depend mainly on the data length of the transmissiondata. In the present embodiment, the time interval may be set using anarbitrary time unit as with the data length, and thereby, the period oftime during which the information channel is no used may be reduced soas to realize efficient information downloading.

FIG. 9 shows a configuration of a portion of a mobile terminal 900 thatmay be suitably used in the second embodiment of the present invention.It is noted that elements of the present embodiment that are identicalto those shown in FIG. 6 are assigned the same numerical references anddescriptions thereof are omitted. In the present example, a receptionsignal that is received from an antenna is demodulated through ademodulation circuit (not shown), and control data from the controlchannel are input to a control channel decoding unit 502. Then, at adetermination unit 504, a determination is made as to whether downloadinformation exists, and the determination result is reported to aninformation channel timing generating unit 506. If it is determined thatdownload information exists, information on the data length of thedownload information and the offset are further extracted from thecontrol data at an extracting unit 512, and the extracted information isconveyed to the information channel timing generating unit 506. Then, aninformation channel decoding unit 516 receives the download informationbased on the reception timing from the information channel timinggenerating unit 506, and decodes the download information to obtaininformation data.

According to the present embodiment, the offset may be changed withrespect to each group in transmitting download information. The length(duration) of the offset is reported to each group through the controlchannel. Also, the offset may be suitably determined by the scheduler304 within the information downloading apparatus 300 so that informationdownloading efficiency may be improved.

Third Embodiment

A third embodiment of the present invention generally corresponds to acombination of the features of the first embodiment and the secondembodiment of the present invention. Specifically, in the presentembodiment, plural information channels are used, and the offset isarranged to be variable. It is noted that the elements of the presentembodiment that are identical to those of the first and/or secondembodiment are assigned the same numerical references and descriptionsthereof are omitted.

FIG. 10 is a block diagram showing a configuration of an informationdownloading apparatus 1000 according to the third embodiment. In thepresent embodiment, a scheduler 1004 determines the existence ofdownload information, the offset, the channel number, and the datalength, and reports the determination result to the control channelgenerating unit 1008. In the control channel generating unit 1008, acontrol channel that includes the above information is generated.Information pertaining to the offset is also supplied to the informationchannel timing generating unit 1020. The information pertaining to thechannel number is also supplied to the selector 312.

FIG. 11 is a block diagram showing a configuration of a portion of amobile terminal 1100 that may be suitably used in the third embodiment.In the present example, control data from the control channel are inputto the control channel decoding unit 502 to be decoded thereat. Then, adetermination unit 504 determines whether download information existsand reports the determination result to an information channel timinggenerating unit 506. If it is determined that download informationexists, information pertaining to the data length of the downloadinformation, the offset, and the channel number are extracted at anextracting unit 512. The offset and the data length are also reported tothe information channel timing generating unit 506. The channel numberof the information channel to be used is reported to the channelswitching unit 514 through the extracting unit 512 so that the channelis set to the appropriate information channel. Then, an informationchannel decoding unit 516 receives the download information based on thereception timing from the information channel timing generating unit506, and decodes the download information to obtain information data.

According to the present embodiment, plural information channels areused, and the offset may differ depending on each group upontransmitting download information. In this way, efficient informationdownloading may be realized, and information may be quickly downloadedwhile improving the usage efficiency of communication resources for theinformation channels. It is noted that in the first example, informationmay be quickly downloaded to each group but the usage efficiency of eachindividual information channel is low. In the second embodiment, theinformation channel usage efficiency is very high but the informationdownloading timing is delayed compared to the first embodiment.According to the present embodiment, a time directional offset and afrequency (or spread code) may be dynamically assigned according to theamount of transmission data that are stored in the buffer. Since thechannel number of the information channel and the offset may be suitablyadjusted in the present embodiment, the scheduler 1004 may be configuredto select a suitable channel number and a suitable offset value for eachdownloading operation.

Fourth Embodiment

FIG. 12 is a block diagram showing a configuration of an informationdownloading apparatus 1200 according to a fourth embodiment of thepresent invention. It is noted that elements of the present embodimentthat are identical to those of the first through third embodiment areassigned the same numerical references and description thereof areomitted. In the present embodiment, a scheduler 1004 determines theexistence of download information, the offset, the channel number, andthe data length based on information from a buffer 302. Of thedetermination results, information on the existence of downloadinformation is reported to a main control channel generating unit 1202,and information pertaining to the data length, the offset, and thechannel number are reported to a sun control channel generating unit1204. As is described, in the present embodiment, a main control channelgenerating unit 1202 for transmitting information indicating theexistence (or non-existence) of download information, and a sub controlchannel generating unit 1204 for transmitting other control data (e.g.,data length, offset, and channel number) are used. The main controlchannel and the sub control channel are each made up of time slots thatare allotted to the respective groups. The offset (deviation) betweenthese control channels are maintained at zero or a fixed value.

FIG. 13 shows an exemplary set of a main control channel, a sub controlchannel, and information channels 1, 2, and 3 that may be output in thepresent embodiment. According to the present example, in time slot (i)of the main control channel, it is indicated that download informationexists, and in a corresponding time slot (i′) of the sub controlchannel, the data length, the offset, and the channel number areindicated. Accordingly, after the elapse of offset time Ti from the endof the time slot (i′), the download information may be transmitted usinginformation channel 1, for example. Similarly, in another time slot (j)of the main control channel, it is indicated that download informationexists, and in a corresponding time slot (j′) of the sub controlchannel, the data length, the offset, and the channel number areindicated. Accordingly, after the elapse of offset time Tj from the endof the time slot (j′), the download information may be transmitted usinginformation channel 2, for example. In another time slot (k) of the maincontrol channel, it is indicated that download information does notexist, and in this case there is not information that is to betransmitted at the sub control channel. In the present embodiment, thetemporal difference between the main control channel and the sub controlchannel is maintained at a predetermined offset values Td; however, theoffsets Ti and Tj indicating the offset for starting the transmission ofdownload information correspond to variables that may be suitablyadjusted

FIG. 14 is a block diagram showing a configuration of a portion of amobile terminal 1400 that may be suitably used in the fourth embodiment.In the present example, the control channel is divided into twochannels, namely, the control channel and the sub control channel uponbeing transmitted. Accordingly, the mobile terminal 1400 of the presentembodiment includes a main control channel decoding unit 1402 and a subcontrol channel decoding unit 1404. The main control channel decodingunit 1402 decodes the information included in the main control channeland conveys the decoded information to a determination unit 504. Thedetermination unit 504 determines whether download information existsand reports the determination result to an information channel timinggenerating unit 506. Other control data are supplied to the extractingunit 512 through the sub control channel decoding unit 1404 wherein thedata length, the offset, and the channel number are extracted at units508, 509, and 510, respectively. The data length and the channel numberare then supplied to a channel switching unit 514, and accordingly, datain the information channel may be received through an informationchannel decoding unit 516.

According to the present embodiment, features and advantages that aresimilar to those of the third embodiment are realized, and additionally,the control channel is divided into a main control channel and a subcontrol channel. For example, a conventional paging indicator channel(PICH) may be used as the main control channel for transmittinginformation pertaining to the existence of the transmission data, and anassociated S-CCP channel may be used as the sub control channel fortransmitting other information. Accordingly, in the present embodiment,conventional technology may be applied to achieve desired effects of thepresent invention with relative ease.

Fifth Embodiment

FIG. 15 is a block diagram showing a configuration of an informationdownloading apparatus according to a fifth embodiment of the presentinvention. The present embodiment is generally identical to the thirdembodiment except for the manner in which the data length of thedownload information is handled. In the first through fourthembodiments, information pertaining to the data length is transmittedthrough the control channel; however, in the present embodiment,information on the data length is transmitted through the informationchannel. Specifically, the data length information is inserted in theinformation channel to be used as header information.

In the present embodiment, a scheduler 1504 determines whether downloadinformation exists, the offset, the channel number, and the data lengthof the download information as in the previously described embodiments.Then, information on the data length is supplied to an input on one sideof an adder 1503. The input on the other side of the adder 1503 iscoupled to an output of a buffer 302. This adder 1503 may attach theinformation pertaining to the data length as header information for thedownload information. The download information having the informationpertaining to the data length attached thereto is conveyed to a suitableinformation channel generating unit through a selector 312, and istransmitted therefrom.

FIG. 16 is a diagram showing an exemplary set of a control channel andan information channel that may be used in the fifth embodiment of thepresent invention. According to this example, each time slot 1602 isallotted to one of plural multicast groups, and for each groupinformation pertaining to the existence of transmission data(information existence) 1604, the information channel to be used iftransmission data exist (channel number) 1606, the offset 1608 aretransmitted. After the end of a given time slot and after a designatedoffset time T provided by the offset 1608 elapses, the transmission ofthe download information may start. In the information channel beingillustrated, the data length of the download information 1612, thedownload information 1614, and a CRC 1616 are transmitted. It is notedthat the CRC is not a prerequisite of the present invention and maytherefore be omitted as necessary or desired.

FIG. 17 is a block diagram showing a configuration of a portion of amobile terminal 1700 that may be suitably used in the fifth embodimentof the present invention. The mobile terminal 1700 of the presentexample is generally identical to the mobile terminal 1100 of FIG. 3,except for the manner in which it handles information on the data lengthof download information. According to the present embodiment, the datalength is transmitted as header information in an information channel,and thereby, information on the data length is extracted at aninformation channel decoding unit 516, and is supplied to an informationchannel timing generating unit 506. The present embodiment may beadvantageous in that the amount of information contents to betransmitted by the control channel may be reduced.

Sixth Embodiment

FIG. 18 is a diagram illustrating an exemplary set of control channelsand information channels according to a sixth embodiment of the presentinvention. According to the present embodiment, a first control channeland a second control channel are provided to conduct paralleltransmission of control data to two groups. In the example illustratedin the drawing, transmission of control data with respect to the groupscorresponding to time slots 0 through 63 may be conducted by the firstcontrol channel, and transmission of control data with respect to thegroups corresponding to the time slots 64 through 127 may be conductedby the second control channel. For example, three sets of downloadinformation that are offset by offsets T₀, T₁, and T₆₅ from time slots0, 1, and 65, respectively, may be transmitted by information channel 1,and download information offset by T₆₄ from time slot 64 may betransmitted by information channel 2.

According to the present embodiment, the control channel generating unitof the transmission unit uses plural time slots that may temporallyoverlap to transmit information on the existence of downloadinformation, the information channel to be used if the downloadinformation exists, the transmission timing of transmission data, andthe data length of the transmission data to plural groups. By providingplural control channels as in the present embodiment, the control datafor plural groups may be transmitted in a parallel manner. The presentembodiment may be particularly advantageous for systems in which arelatively large number of groups exist.

According to an embodiment of the present invention, the scheduler maybe configured to select an information channel from plural informationchannels and determine to conduct transmission of transmission data withthe selected information channel so that transmission data withdiffering destinations may be transmitted through differing informationchannels. The transmission unit may be configured to transmit to eachgroup, information pertaining to the existence of transmission data, theinformation channel to be used if the transmission data exist, and thedata length of the transmission data through the control channel. Thecontrol channel includes plural time slots that are each associated withone of plural groups. Download information for the respective groups maybe quickly downloaded through plural information channels so that thedata downloading efficiency may be improved.

Also, according to another embodiment of the present invention, thescheduler may be configured to determine the transmission timing fortransmitting the transmission data for each group based on the datalength of the transmission data that is stored in the buffer. Thetransmission unit may be configured to transmit for each group,information pertaining to the existence of transmission data, thetransmission timing if the transmission data exist, and the data lengthof the transmission data through the control channel. The transmissiontiming (start time and end time) may be determined according to a givendata length, and thereby, data downloading efficiency may be improved.

An information downloading apparatus according to an embodiment of thepresent invention may be implemented in a base station that conductswireless communication with a mobile terminal, or alternatively, theinformation downloading apparatus may be implemented in a superordinateapparatus that controls the base station, for example. The informationdownloading apparatus may be made up of one single apparatus, or pluralapparatuses. For example, the scheduler (304, 704, 1004, 1504) and thetransmission unit (306) may be provided in separate apparatuses. Inother words, the information downloading apparatus of the presentinvention may be realized in any form so long as its characteristicfeatures may ultimately be realized.

It is noted that preferred embodiments of the present invention havebeen described above; however, the present invention is not limited tothese embodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

1. A wireless communication apparatus, comprising: a receiving unit thatreceives data frequency information for transmitting data to a multicastgroup and offset information indicating an offset amount of a timing atwhich the data is to be transmitted with respect to a predeterminedperiodic reference timing, and receives the data being transmitted tothe multicast group using a frequency determined by the frequencyinformation at a transmission timing determined by the offsetinformation; and wherein the receiving unit receives the data beingtransmitted to the multicast group at a timing determined by the offsetamount indicated by the offset information, which is transmitted priorto transmission of the data each time data transmission is to beperformed.
 2. The wireless communication apparatus as claimed in claim1, wherein the data being transmitted to the multicast group includes aportion that temporally overlaps with another set of data beingtransmitted using a different frequency.
 3. The wireless communicationapparatus as claimed in claim 1, wherein the data corresponds tovariable length data.
 4. A multicast data receiving method for awireless communication apparatus, the method comprising: receiving datafrequency information for transmitting data to a multicast group andoffset information indicating an offset amount of a timing at which thedata is to be transmitted with respect to a predetermined periodicreference timing; and receiving the data being transmitted to themulticast group using a frequency determined by the frequencyinformation at a transmission timing determined by the offsetinformation; wherein the data being transmitted to the multicast groupis received at a timing determined by the offset amount indicated by theoffset information, which is transmitted prior to transmission of thedata each time data transmission is to be performed.
 5. The multicastdata receiving method as claimed in claim 4, wherein the data beingtransmitted to the multicast group includes a portion that temporallyoverlaps with another set of data being transmitted using a differentfrequency.
 6. The multicast data receiving method as claimed in claim 4,wherein the data corresponds to variable length data.